What does a paleontologist study?
_____________________ is used to determine the age of a rock layer.
The preserved remains of trace fossils is called an _______________________fossils.
Foot prints and trails are examples of _________________________________fossils.
What is a petrified fossil?
a fossil formed when minerals replace all or part of an organism
What does uniformitarianism mean?
processes that continue to reshape the earth
What does catastrophism mean?
all geologic change occurs suddenly
What is the absolute age of a rock? What is your absolute age?
the exact age
What is the relative age of a rock? What is your relative age (compare to a sibling)?
whether the rock is younger or older
What do scientists need to know in order to find the absolute age of a rock?
the relative age of the rock
Which method of radiometric dating was used to determine the age of the Earth?
the geologic time scale
The _______________________ states that the youngest rock layers are at the top of the oldest rock layers are at the bottom. This helps determine the ______________ of the ages of the rock.
law of superposition; absolute age
What is an unconformity? Give four examples.
erosion has caused an older rock layer to be exposed, and then a newer rock layer forms on top of it. examples: erosion, non-deposition, non-conformity and disconformity
The ______________________ shows how life has changed on Earth, as well as the major events in Earth's history?
geologic time scale
_____________________ describes the process of how living things on Earth have changed over long period of time.
A Dodo bird is ____________________ because it no longer exists on Earth.
What are the three ERAS that geologic time is divided into?
Paleozoic, Mesozoic, Cenozoic
What ERA are we currently in?
What is the name of the large landmass (supercontinent) that existed more than 250 million years ago? ___________________________
What do scientists think may have caused dinosaurs to become extinct?
a meteorite hit earth and the climate changed
Approximately how old is the Earth?
4.6 billion years old
What have scientist learned by studying Earth's fossil record?
the history of life on earth
What type of condition slow down an organisms decay?